Minimizing and/or increasing the beam width of a beam of light are important in a number of technology areas. For example, a minimized, or “spot size” of a focused beam of light is important for writing data to, or reading data from, an optical disk.
A cross-sectional view of a conventional lens device 10 is depicted in FIG. 1. As shown therein, the conventional lens device 10 includes a plurality of lens elements 14 positioned on a substrate 12. The lens elements 14 have heights 20 and widths 22 that are at least 200 microns due to the current manufacturing processes available and the refractive index of the material used to fabricate the lens elements 14.
In order to obtain a small spot size, a beam is typically passed through the lens elements 14, which have a relatively high numerical aperture (“NA”). The NA of a convex lens can be increased by increasing the diameter of the lens and shortening its focal length. However, incorporating such lenses in optical-based devices may be cost prohibitive because of the difficulty in fabricating very small lenses with large curvatures and because of the precise polishing needed to make the lenses aberration free. In addition, conventional convex and concave lenses may not be compatible with planar integrated circuits.